Composition of tall oil and aromatic oil and method of making it



Patented Dec. 18, 1951 COMPOSITION OF TALL OIL AND AROMATIC OIL AND METHOD OF MAKING IT Edward A. Van Valkenburgh, Greene, N. Y.

No Drawing. Application October 14, 1950, Serial No. 190,245

7 Claims. (Cl. 106-423) This invention relates to compositions for use in the compounding and vulcanization of rubber, and particularly of synthetic rubber, and to method of producing such compositions.

This application is a continuation-impart of my prior application Serial No. 627,103, filed November 6, 1945, now abandoned.

The new compositions of the present invention are homogeneous, liquid compositions made by blending heat treated crude tall oil with a relatively small amount of a non-volatile aromatic oil to give a stable, permanently liquid composition having special advantages for use in the compounding of GR-S synthetic rubbers and mixtures of GR-S synthetic rubber and natural crude rubber. The GR-S synthetic rubbers are copolymers of butadiene andstyrene known as Buna S and designated by U. S. Rubber Reserve as GR-S.

Crude tall oil acids are produced as a byproduct from the paper pulp industry and are made up largely of resin acids and fatty acids, e. g., around 50% of resin acids and 40% of fatty acids and around 10% of unsaponifiable material such as sterols and high molecular weight aliphatic alcohols. Such crude products form a semi-solid non-homogeneous mass on standingand may separate into an upper liquid and lower solid or semi-solid layer. Such crude products are not well adapted for use in rubber compounding. It has been'proposed to heat tall oil to high temperatures for prolonged periods of time but even such products when made from crude tall oil tend to develop semi-solid separation which is highly undesirable from thestandpoint of rubber compounding, not only on account of handling difliculties but especially because of nonuniformity.

The'present invention overcomes the dilficulties and objections incident to the use of such prior products and provides a new liquid, homogeneous composition which has special advantages for use in GR-S compounding.

According to the present invention the crude tall oil is subjected to a heat treatment which can advantageously be much less than the heat treatments to which tall oil has heretofore been subjected and there is then added to the heat treated tall oil a small and regulated amount'of a non-volatile aromatic oil which blends therewith to give a permanently liquid, stable and homogeneous composition which can be readily weighed and quantitatively poured from a container and which is a valuable composition with GR-S synthetic rubber as well as with mixtures of GR-S and naturalcrude rubber.

35 540 F., containing around '85% 10 tar oil, or a petroleum aromatic oil, such as is obtainable by sulfur dioxide extraction of certain crude oils, or such as is produced in high temperature catalytic cracking processes where fractions are obtained high in aromatic constituents.

l5 7 Where the non-volatile aromatic oil is a coal tar oil, it is advantageously one which is largely freed from crystallizable anthracene salts, such as the product sold under the trade name Bardol of the Barrett Company, said product being a coal tar distillate having a specific gravity of about 1.08 to about 1.12, a minimum flash point of about 100 C., with not more than 10% distilling between 210 C. and 235 C. and from 30 to 60% distilling up to 300 C. In general, only small amounts of the aromatic oil are used, e. g., 10 to by weight of the composition, and advantageously between 10 and 15% by weight of the composition.

The non-volatile aromatic petroleum oil is ad- 30 vantageously an oil such as the product known in the trade as Esso Heavy Aromatic Naphtha N0. 132, with a specific gravity of 0.905, a flash point of 121, an initial boiling point of 328 with 90% boiling at 489, and a final boiling point of aromatics Another advantageous type of non-volatile" petroleumaromatic hydrocarbons is that obtained by the vacuum distillation-catalytic cracking process with fractionation of the products to give fractions containing aromatics as the principal constituent and with the remainder of the fraction made up largely of naphthenes, which are unsaturated,'with small amounts of olefins. Such high aromatic fractions have a flash point of 175 F.,or higher, an initial boiling point of 386 F.,

or higher, a specific gravity of 0.919 and a final boiling point around 551 F. and with a percentage of aromatics of e. g. 60% to 70% or more, and with a balance largely of unsaturated naphthenes and a small amount of olefins, with a large proportion of the aromatic components in 7 the form of alkylated naphthylenes.

The compounding process is advantageously carried out by heating the crude tall oil with continued agitation, e. g., to around 350 F; for

half an hour or somewhat longer and by'then 3 adding the aromatic oil to the hot, liquid, heattreated tall oil with continued stirring while the composition is cooled. This gives a stable, nonresinous, liquid product especially valuable for compounding GR-S synthetic rubber.

Th proportions of aromatic oil can be somewhat varied with the heat treatment to which the tall oil is subjected. In general, the amount of added aromatic oil should not be too high but should be sufficient to insure homogeneous liquid products. I

In addition to adding the aromatic oil small and varying amounts of other compounding. ingredients can be added in some cases, e g petroleum oils, asphalts, etc.

While I do not desire to limit myself by any theoretical explanation, I am led to believe that the heat treatment of the tall oil brings about desirable. changes, either physical or chemical since. the heat treated tall. oil can be compounded with thecoal tar oil to give a stable, homogeneous liquid whereas the crude untreated tall; oil does not form such compositions .with aromatic oils. It may be that in, addition to any, physical changes that take. placethere is a change in, the resin acids which results in, the.,modif lcation of the resin acids and the formation of appreciable i ing the aromatic oil and during the blending amounts of dehydroabietic acid and dihydroabietic acid. Whatever the. theoretical explanation. may be, theheat. treated, crude tall oil has a desirable compatibility with aromatic oil in small amount which the. untreated crude tall, oil

acids. dov not have. and gives a. valuable liquid,

rosins which tend. to produce excessive or undee sirable rubber to metal tackinessin theuncured stocks, causing troublesome sticking to the. mill and calender rolls, and also tending to. retard the cure. I

e ew. comp sitio a o a v ablecomm- P sition, for rubber compounding because of its compatibility with GR s synthetic rubber and in mixtures of GRFS- syntheticrubber and natural rubber.

' Oneof the. advantages obtained GR-S rubber compounding with the use of the new compo sition is a desirable and marked improvement. in cut-growth resistance of the cured products.

The new composition is valuable for use as-an activation acid on account of its chemical ef feot upon the .zinc oxide and. organicaccelerators. in the GR-S rubber compositions, being a valu able substitute for the more expensive stearic acid commonly used. Thus I have made, e. g., of 87% of heat treated tall oil acids. and 13% of non-volatile coal tar oil (Bardoi can satisfactorily be used to replace. the much more expensive stearic acid in GR-S tire treads and: a similar activation obtained with the use of a. somewhat increased amount of the new composi-. tion. The new composition has the further a.d-. vantage of improved mixing, efficiency, superior raw processability, better uncured rubber to rub-. ber tackiness andv non-bloom effect before. and; after vulcanization than stearicacid.

When non-volatile petroleum aromatic oils are found that the new composition operation, since it aids in removing some of e the more volatile and odoriferous constituents.

Steam distillation may also remove some of the aromatic oil, particularly more volatile components thereof.

From the standpoint of producing the new composition, it can be produced from crude. tall oil which is readily available and which is a cheap raw material and the heat treatment can be carried out, at. moderate expense with subsequentblending of a small amount of the aromatic oil to produce a uniform, stable, activating and plasticiing liquid which is highly compatible with a uncured butadiene GR-S copolymer in synthetic rubber compounding and gives improved cutgrowth resistance after vulcanization.

While. in. general, within the limits of com.- patibility, theheat treatment of the crude tall oil may be at lower temperatures or have shorter times withsomewhatlarger amounts of the coal tar oil, it is. desirable from the standpoint of cured. rubber quality not touse too large amounts of the aromatic oil. particularly for GRPS tire tread compounding, since the use of excessive amounts of coal tar oil tends to lower. the modulus and cured hardness of the vulcanized rubber.

The invention will be further illustrated by the. following specific example giving an advan-v tageous method of; carrying out the process of mekine the ew om o t n nd producing a compositionhaving desirableproperties for GR-S b er c m e dins Crude, unrefined American. tall oil (the Liqro product of the West Virginia Pulp & PaperCompany) is heated with continuous mechanical agitation for about half an hour at around 260 F; and there then rapidly added with continued mechanical stirring an amount of non-volatile coal tar oil (Bardolof the BarrettCompany). in the proportions of 13 parts by weight of the coal taroil to. 87: parts, by weight of the heat treated crude tall oil. The mechanical agita tionis: continued while the product is cooled and it can; then be. drawn off, e. g into drums or. tank-cars for shipment.

The composite product so. produced having an acid number of around 150 was an excellent stable liquid product having valuable'properties as an activation acid in GRe-S rubbercom: pounding. The. addition of 13% of the coal tan oilto the heat treated crudetall oil resulted inthe production of a permanent liquid product highly compatible with, GR-S- and with mixtures of GRr-S and natural crude rubber.

As regards, reduction of. rubber to metal tackiness, 7 parts of this, composition per 100. parts.

it was not sufficiently tacky to go over to the back roll of the mill. 1 "With respect to plasticizing efliciency in a high zinc oxide, Captax (mercapto-benzothiazole) accelerated, GR-S test compound, 7.5 parts of theabove composition per l00-parts of GR-S were tested in comparison with the same ratio of gum rosin (J. M. Hubers Turgum). The Mooney plasticity values after 1.5 minutes respectively were 55 for the rubber compound made with the new composition and 68 for the rubber compound made with the gum rosin, showing the marked improvement of the new composition as a plasticizing agent.

As regarding reduced cure retardation, in a Monex (tetra-methyl-thiuram-monosu1fide) accelerated'belt friction stock, 20 parts of the above composition per 100 parts of GR-S rubber were compared with a similar ratio of hydrogenated rosin (the Hercules Powder Companys Staybelite resin). Standard scorch tests made with the Mooney plastometer showed that the compound madewith the new composition was precured in 30 minutes, whereas 66 minutes were required for the stock containing the Staybelite resin, thus showing the reduced cure retardation effect of the new composition as compared with that of the hydrogenated rosin.

Moreover, for these same belt friction stocks, the Shore hardness values for samples cured 20 minutes at 40 pounds steam pressure, respectively, were 54 for the product in which the new composition is used and 47 for the compound in which hydrogenated rosin was used, indicating the faster curing obtained with the new composition.

The invention will be further illustrated by the following example showing the suitability of the new composition for GR-S tire tread compound in direct comparison with a similar tire tread compound containing a similar amount of a liquid asphalt (the C. P. Hall Companys Paraflux). The following compositions were used:

GR-S rubber 100 100 Easy Proc. Channel Black 45 45 Zinc oxide 2.4 2.4 Sulfur 2 2 Santocure (activated mercaptobenzothiazol) Monsanto 1.2 1.2 Asphalt (Parafiux) 10.4 New composition 10.4

Minutes Cured Per Cent Elongation In GR-S tire treads it is important to maintain a high ultimate elongation, especially on long overcures, and the values given above show the superiority of the new composition as contrasted with the use of the asphalt softener.

The invention will be further illustrated by 6" the following example "using a composition of heat treated tall 'oil and aromatic oil from pctroleum. i

The composition is made by heat treating the tall oil for one hour at about 300 to 350 F. and by similarly preheating the aromatic oil at a similar temperature for a period of one hour, with agitation during heating and, advantageously, with steam agitation. The preheated aromatic oil is then added gradually to the heat treated tall oil, either with mechanical stirring, or with agitation by steam, to form the homogeneous composition. The proportions of heat treated tall oil and aromatic oil are approximately of heat treated tall oil and 25% of aromatic oil, the aromatic 011, containing upwards of 60% aromatics, the remainder being principally unsaturated naphthenes with a small amount of olefins, known inthe-trade as Esso Aromatic Naphtha No. 180 with a specific gravity of 01919, a flash point of 178- F., and an initial boiling point of 386 F., with boiling upwards of 526 F., and a final boiling point of 551 F.

This composition was used in two GR-S tire tread compounds having the following compositions:

Y Parts Parts GR-S rubber (X-478) .l 100 High abrasion furnace black (Phillips Philblack-0). 50 50 Zinc Oxide... 3 3 Sulfur 2 2 Santocure (activated mercaptobcnzot azol) Monsanto 1. 2 l. 2 Circe oil (Sun Oil Co. naphthenic 0il)--. i 5 1 New composition 4 8 The above compounds were cured at 287 F. over a range of cures and the following values were obtained showing tensile strength and final elongation for the two compounds:

I II Minutes Cured Elongation Tensile Elongation These compounds were subjected to tests for 300% modulus and 500% modulus and for Shore Creep with the following results:

I II

Minutes Cured s The new composition can similarly be used in commercial truck tire treads to replace stearic acid, giving superior raw processing properties and similar cured quality.

It will thus be seen that the present invention provides a new and iinproved tall oil composition made from cheap crude tall oil which overcomes the objections to the use of crude tall oil and converts it by a process of heat treatment and blending with a non-volatile aromatic oil to a homogeneous, liquid composition particularly advantageous for use in the compounding of synthetic rubbers and particularly GR-S synthetic u ber: welt. as;miztturesav 61; Synthetic and natural rubbers.

I Iaciaim;

sisting: for; the; most: part; oi: heat; treated. crude tail oiltpreheated to aatemperature: excess; of: about260 F; and biendedywith asmailenproportion' of, non-volatile; aromatic. oi-i,,said; propor.- tions being;- froma about 10; to:;30% of the-heat treated product;

2. A new composition. fon'compoundingq with- GR-S(syntheticirubber:andmixturesof-suchrub? her: with natural rubber;1saidqcompositioneonsiste ing; essentiailsgofiheat treatedgcrudetaliqoi-i preheated toga t'emp erature inw excessof; about 260 E: and; blended with: about.- ;10to;1-5:% of; non. volatile; aromatic; oil. 7

3; The method of: producing a. homogeneous.- liquidcomposition for: use-- in synthetic? rubber compounding which: comprises; heat treating crudeitali oil by heating .to-ameievated; temperature of about 3-50-F. for-a: period of about onehalf to one and one-half hours and blending w-itha the hot, heat treated. oi1.a smaller. proportion of. about 10 to 30% of non-volatile, liquid aromatic oil.

4'. The method of producing a homogeneous liquidf composition foruse insyntheticrubber compounding; which; comprises heat treating:

crude-:talioil to'a temperatureoiaround 260 to 400 F. for from one-half, totone and. one-halt hours to heat treat the oil andsblending withthe hot, heat treated. oil about 10-to 30%. of anonvoiatileraromatic-oil. p

5-. The method. of. producing ahomogeneous. liquid composition for use"- in synthetic. rubber. compounding. which comprises heat: treating, crude taiLoil to"a temperature of aroundv 260 to 400 F; for-a" suflicient time to heat? treat-the oiland blending. withthezhot; heat treated oii about 10 to. 15% Ma non-volatiie-aromatic oi1.-

6*. A composition as defined inciaimi in. which thenon-volatiiearomatic oil is -a coal tar oil:

7. A composition as=.-defined-in:c1aim 1 in which they nonevolatile aromatic oilis: an. aromatic petroleum oii-..

EDWARD A-.. VAN VALKENBURGH;

REFERENCES CITED The following v references" are of: record in the file of this. patent:

UNITED STATES PATENTS Number Name Date. 23143368; Dal'y .Mar. '7; 1944. 23928.63 Rudd Jan. 15, 1946' 2,421,627" La Crosse June 3,194? 2,448,605. Kleinicke Sept. 7;.1948

FOREIGN PATENTS.

Number. Country Date 229,296" Great'Britain May 10; 1926' 45,534, Sweden Jun-e"18;. 1'91'9 

1. A NEW COMPOSITION FOR COMPOUNDING WITH GR-S SYNTHETIC RUBBER AND MIXTURES OF SUCH RUBBER WITH NATURAL RUBBER, SAID COMPOSITION CONSISTING FOR THE MOST PART OF HEAT TREATED CRUDE TALL OIL PREHEATED TO A TEMPERATURE IN EXCESS OF ABOUT 260* F. AND BLENDED WITH A SMALLER PROPORTION OF NON-VOLATILE AROMATIC OIL, SAID PROPORTIONS BEING FROM ABOUT 10 TO 30% OF THE HEAT TREATED PRODUCT. 